<!DOCTYPE html>
<html lang="en">
	<head>
		<meta charset="UTF-8">
		<title>Title</title>
		<style>
      .box{
        width: 400px;
        border: 10px solid #000;

        /* overflow  position 都能形成bfc */
        /* overflow: hidden; */ 

        position: absolute;
      }

      .c1{
        float: left;
        width: 200px;
        height: 200px;
        background-color: blue;
      }
      .c2{

        float: left;
        width: 200px;
        height: 200px;
        background-color: pink;

      }
		</style>
	</head>
	<body>
		<div class="box">
      <div class="c1"></div>
      <div class="c2"></div>
    </div>

    
	</body>
</html>
